Density = mass/volume
Density = 40g/20cm^3
Density = 2g/cm^3
Answer:
(a). The ball's centripetal acceleration is 
(b). The magnitude of the net force is 232.9 N.
Explanation:
Given that,
Mass of baseball = 144 g
Speed = 81 mph = 36.2 m/s
Distance = 81 cm
(a). We need top calculate the ball's centripetal acceleration just before it is released
Using formula of centripetal acceleration

Where, v = speed
r = radius
Put the value into the formula



(b). We need to calculate the magnitude of the net force that is acting on the ball just before it is released
Using formula of force

Put the value into the formula


Hence, (a). The ball's centripetal acceleration is 
(b). The magnitude of the net force is 232.9 N.
If 50 identical light bulbs are connected in series across
a single power source, then the voltage across each bulb
is ( 1/50 ) of the voltage delivered by the power source.
Answer:
Explanation:
Magnitude of frictional force = μ mg
μ is either static or kinetic friction.
To start the crate moving , static friction is calculated .
a ) To start crate moving , force required = μ mg where μ is coefficient of static friction .
force required =.517 x 56.6 x 9.8 = 286.76 N .
b ) to slide the crate across the dock at a constant speed , force required
= μ mg where μ is coefficient of kinetic friction , where μ is kinetic friction
= .26 x 56.6 x 9.8 = 144.21 N .
The correct answer is b).